Automated deforestation alerts using Landsat satellite imagery

In 2013 Hansen et al. used Landsat satellite imagery to map global forest loss and gain from 2000 to 2012 at a spatial resolution of 30 meters. This was the first study to quantify a globally consistent record of forest change. Using these techniques the University of Maryland prepares a weekly set of alerts, called GLAD alerts, which identify 30-meter pixels (from a total of about a billion pixels) that have recently been cleared. Although the data are updated on a weekly basis, the amount of time between detections depends on cloud cover. Persistent cloud coverage found in many tropical countries limits the monitoring frequency, in some cases for months at a time. Alerts become confirmed when more than one Landsat image flags the pixel as an alert. GLAD alerts are currently available for 16 tropical countries; Brazil, Burundi, Brunei, Peru, Cameroon, East Timor, Central African Republic, Indonesia, Democratic Republic of Congo, Malaysia, Equatorial Guinea, Papua New Guinea, Gabon, Republic of Congo, Rwanda, and Uganda.

Latest research supports the work many years ago of Robert Howarth at Cornell who argued that leakages and other abnormal emissions of methane during fracking and other oil and gas operations erased the carbon advantage of natural gas over coal.

Environmental Indexes

From Our Files

In this new study an analysis of new global ocean and land temperature data with corrections to older shipboard measurements reveals that the temperature trend over the period 2000-2014 does not differ from the temperature trend over the period 1950-1999. It is concluded that the “hiatus” reported in IPCC AR5 is most likely an artifact of older measurement techniques.

Atmospheric methane concentration plateaued leading up to 2006, but began to rise again in 2007. The source of the increase has been widely debated, but using satellite imagery a recent study has found that the increase can be ascribed to increased fossil fuels and livestock sources in roughly equal measure.

Approximately 800,000 years ago something changed in the Earth’s climate system that led to the climate then following a series of approximately 100,000 year cycles. Small, predictable changes in the Earth’s orbit about the Sun act as triggers for the glacial and interglacial periods, but other factors such as ice sheet volume, CO2 concentration, and biological feedback mechanisms are also involved.

In this study the global average surface temperature over the past 2 million years has been derived from deep sea cores. The results reveal that global cooling occurred about 300,000 years before the rapid ice sheet growth and the development of the first 100,000-year glacial/deglacial cycle about 800,000 years ago.